This invention relates generally to mounting and stowage mechanisms and more particularly is directed to a mechanism which mounts a head-up display combiner in a aircraft cockpit or the like for positioning in the pilot's line-of-sight and for swinging the combiner into a stowage position. The mechanism is designed so that vibration, mechanical play and other variations cause minimal effect on the optical properties of the display. The mechanism includes stops which come into play in both the active and stowed positions for loading the mechanism bearings to minimize vibration.
When the pilot is in his cockpit, he has a normal forward line-of-sight through the windscreen. This line-of-sight is generally the vector upon which the aircraft is flying. In addition to viewing the outside world in the forward direction, the pilot must also keep apprised of various other information. He has in front of him an extensive instrument panel which provides various information relating to the operational status of the aircraft and various navigational information such as heading, altitude, speed, and the like. Other information, such as weapons delivery information, may be supplied by computers and radars in military fighter aircraft.
In high-performance aircraft, it is difficult to properly observe the scene through the windscreen while simultaneously observing the panel displays which provide the data necessary for proper aircraft and weapons operation. This problem is compounded in military aircraft where there may be adversary aircraft and/or adversary anit-aircraft missiles within a dangerous range. Adversary information is often collected by radar, and, in the past, the information had been provided on cockpit panel displays. Thus, the pilot had to divide his attention between the panel display and the real world scene through the windscreen.
In order to overcome this difficulty, the head-up display was developed to provide selected information superimposed on the pilot's normal line-of-sight view of the outside world. The information was displayed with a focal length at infinity so that the pilot could observe distant outside scenes in the forward direction through his windscreen and, at the same time, view various flight, navigation and weapons delivery information without readjusting his eyes.
The head-up display includes an information source, such as a cathode ray tube, and various optical elements, such as relay lenses and fold mirrors, mounted in a housing received in an opening in the cockpit instrument panel. The optical elements direct light from the source onto a combiner which extends into the pilot's forward line-of-sight. The combiner combines the information displayed on the source with the pilot's view of the outside world. Known combiners are either partially silvered mirrors or holographic optical elements. The combiner can be thought of as a transparent display screen which presents images thereon without interfering with the pilot's view of the outside world.
It is sometimes required to provide a stowage mechanism which permits the pilot to move the combiner from a stowage position to an active position and to return the combiner from the active position to the stowage position. However, existing mechanisms are problematic in that they interfere with or degrade the optical characteristics of the display and require complex positive locking mechanisms.